Dear Dr. Fuchs,

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PLOS One

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #1: Yes

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously? -->?>

Reviewer #1: Yes

Reviewer #2: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available??>

The PLOS Data policy

Reviewer #1: Yes

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English??>

Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: The authors describe an innovative method for monitoring the efficacy of CPR with regard to cerebral perfusion by way of a customized stiffneck holding ultrasound probes in place. The study was conducted in 102 volunteers; no significant pain / dyscomfort was reported.

This is an interesting development that addresses the potentially insufficient cerebral blood flow / oxygen transport during CPR, reflecting a well-known unmet medical need. Since such a device is highly desirable in clinical practice, both pre- and in-hospital, this descriptive feasibility study undoubtedly warrants publication.

There is only one aspect I would be interested in: The demographic data indicate a large variability (e.g., age 19 – 83 years, BMI 34.4, etc.). It would be interesting to know whether physiological variables such as gender/body weight/neck circumference have any impact on the doppler flow values. E.g., by stratifying the groups at the variable's median, the measurements could be described separately for each group. Alternatively, the mean/median Doppler flow values could also be analyzed in relation to the above-mentioned parameters by regression/correlation analysis.

Reviewer #2: In this paper, the authors describe an advanced device using a neck collar to hands-free and continuously measure blood flow in the CCA. The future goal is to use this device during CPR to assess the effectiveness of the performed CPR in individual cases.

This is a very important question during CPR that is not sufficiently addressed in current research, despite studies using adhesives to attach Doppler probes and neck braces. So far, the success and effectiveness of such devices remain unclear because they are often tricky to place and frequently dislocate during CPR or similar body movements. The introduced model appears promising, as do the results of this preliminary study.

Due to the need of improvements in this field, this paper is significant, and because of the presented feasibility of the new arranged device, this paper should be published.

But there are some points which need to be adressed by the authors in my opinion.

Introduction:

No Flow Time usually refers to the period when no CPR is performed, not even by non-medical personnel. This should be clearly mentioned since it cannot be addressed by the presented device.

Materials and Methods:

Can the device be mounted on any standard neck brace, or does it need to be prefabricated? This is important to me because I want to know if it is necessary to remove an already positioned stiff neck if the patient suffers cardiac arrest during transport (e.g., trauma patient), as this could potentially put the patient at additional risk.

How easy is it to place the collar and the probe, including the time from start to the first measurement? I understand this is a preliminary report under test conditions, but could you estimate how difficult and time-consuming it might be under stress or CPR conditions?

The figure of the collar indicates that intubation or assisted ventilation might be affected during the placement of the collar. Please write one sentence about this potential problem.

Results:

The results are well presented and understandable. The collar does not seem to cause any harm (such as skin lesions) and appears wearable in awake and healthy volunteers, which is a significant advantage of the device compared to adhesives.

Discussion:

While all devices that enhance CPR effectiveness are valuable, the most important are those that can monitor CPR efficacy beyond just pupil size or PaCO2.

Given that rapid, continuous CPR is crucial, the authors should discuss how quickly and easily the device can be positioned during CPR, and whether the process of intubation or assisted ventilation might be affected or delayed by placing the device.

Furthermore, blood flow in the CCA does not always indicate adequate brain perfusion. Elevated ICP from bleeding, edema, or similar causes may impair blood flow to the brain even if CCA values are normal. Since severe hypoxic brain damage is the most common cause of adverse outcomes following CPR, this important point should be briefly noted.

Since this is a preliminary dataset collected under study conditions with healthy volunteers, my comments may seem quite critical. However, these are essential questions for researchers in the field. I would appreciate it if the authors could address at least some of these points in their discussion.

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what does this mean?). If published, this will include your full peer review and any attached files.

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Reviewer #1: No

Reviewer #2: No

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To ensure your figures meet our technical requirements, please review our figure guidelines: https://journals.plos.org/plosone/s/figures

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Using a Stifneck Select Collar™ for hands-free semiautomatic blood flow measurements: a user study

PONE-D-26-13295R1

Dear Dr. Fuchs,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Martin Kieninger

Academic Editor

PLOS One

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

Reviewer #1: (No Response)

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions??>

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously? -->?>

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available??>

The PLOS Data policy

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English??>

Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: My question regarding the influence of baseline parameter on flow values will be addressed in future studies / publications. I therefore have no further aspects to discuss on this paper.

Reviewer #2: In the revised version the comments and concerns of all reviewers were met by the authors. In my opinion the paper does address an important point in the evaluation of efectiveness of CPR and it improved by adderssing the points of the reviewers.

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what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review?  For information about this choice, including consent withdrawal, please see our Privacy Policy

Reviewer #1: No

Reviewer #2: No

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